Mattress cushion



FIG. 1 is a perspective view of a mattress cushion, showing our new design;

FIG. 2 is a front side view of the mattress cushion shown in FIG. 1;

FIG. 3 is a back side view of the mattress cushion shown in FIG. 1;

FIG. 4 is a right side view of the mattress cushion shown in FIG. 1;

FIG. 5 is a left side view of the mattress cushion shown in FIG. 1;

FIG. 6 is a top view of the mattress cushion shown in FIG. 1; and,

FIG. 7 is a bottom view of the mattress cushion shown in FIG. 1.

The broken lines shown in the drawings represent portions of the mattress cushion that form no part of the claimed design. 

CLAIM The ornamental design for a mattress cushion, as shown and described. 